+1 to the corn snake suggestion. They aren't as hefty as a ball python but are cheaper and come in a wicked amount of colour morphs. Ball's are good snakes, but a corn may be a little easier for a beginner to own. There are some very good forums dedicated to snake and reptile keeping, look them up and you will find more info then you could ever imagine.
my 2 cents: You don't need any heat lamps if you've got the right size under tank heat mat to heat up a portion of the tank hot enough. DO NOT buy any sort of heat device that goes into the tank, the snake WILL burn itself eventually.
Don't bother getting the snake from a pet store unless they specialize in reptiles. If you can find one of them, you should be ok, otherwise look for a breeder in your area as well as local reptile expos and shows.
In regards to food, he will need mice and full grown may even take rats, if I remember correctly for the Ball. Feed frozen, avoid live. While frozen does not provide the chase, live rodents could harm or kill your snake. Frozen is much easier to store as well.
Escaping. It will probably happen at least once. Get a good, tight fitting lid, and if you get a ball, you will need something to secure the lid. You can use bricks, books anything heavy. Some lids come with locks, but my favourite is those ratcheting tie down strips that you use on cars tying down stuff. If he does get out, snakes will often go up, or towards heat source. you can lay out a feeder inside a homemade trap to get him back if you can't find him.
the most important thing is probably to do your research and get everything set up( ie heating so you can see the heat fluctuations) a little while before you get him.
good luck